THE UNIVERSE IS EXPANDING
I learned in a class called Descriptive Astronomy that the universe is expanding. Before I begin I would like to say that to me the information I am about to relate is contradictory. Bear this in mind while reading: How can anyone claim that the universe is expanding forever and also claim that our galaxy will be alone in the universe in just 100 billion years? Nonetheless, here is what I learned from an article at the site of NASA.Scientists surveyed the cosmos and measured temperature differences. They detected light created only 379,000 years after the Big Bang, which is an astonishingly short period of time considering the age of the universe. This evidence fits theoretical models of the universe, and so scientists can claim that the universe is indeed expanding, and that it will continue to grow forever.
According to NASA, "The universe is 'flat' in cosmological parlance. In fact, not only won't there be a "Big Crunch", the evidence points to the possibility of a "Big Rip" when the expansion of the universe accelerates. Dark energy, which accounts for roughly 70% of the mass of the universe, has weird gravity that is the opposite of what we know. The gravity that we know attracts; dark energy's gravity repels."
If scientists are right and the universe is continuing to expand and accelerate, our galaxy will be alone in the universe in 100 billion years. That is to say that all other galaxies will be pushed beyond the point of visibility and we won't be able to see them anymore.